Governments are increasingly regulating the exhaust emissions of vehicles. In particular, vehicles powered by diesel engines must meet more and more stringent regulations in the next several years. Cellular ceramic filters have been recognized as being useful in trapping particulates from exhaust emissions. As the filters become clogged, however, they must be regenerated or an unacceptable back pressure develops. A number of positive regeneration systems are known.
The present invention is directed to a regeneration system of a type which uses an electric heater to provide heat for igniting soot or particulates at the inlet end of the monolithic ceramic filter. Once lighted, a flame front advances through the filter to burn away the particulates accumulated thereon. The problem with known systems is that, in general, they are not practical. Either components are designed which are so expensive that the systems are too costly for the consumer or the system has power requirements which would require a different electrical system than is presently available on vehicles, thereby again requiring cost which could not be paid by the consumer. There is, therefore, a need to develop a system which provides non-polluting filtering and regeneration at a power level and system cost which is practical.